Measurements of the isometric contractile forces generated by dog periodontal ligament fibroblasts in vitro.

One hypothesis for the mechanism of tooth eruption is that the periodontal ligament fibroblasts generate the eruptive force. To assess the force generated, these fibroblasts were obtained by explant culture of ligament from mandibular premolars of a dog and were cultured in collagen gel matrices. The forces generated by them under isometric conditions were continuously measured for 120 h with a strain gauge. At the same time the number of cells in the gel was counted and the force measured was calculated as the force generated by 10(4) cells. Shortly after the start of culture, the force per 10(4) cells increased rapidly; it reached 5.2 X 10(-4) N at 8 h, and then remained at the same level for about 48 h. Our findings suggest that fibroblasts of the periodontal ligament may generate sufficient force for tooth eruption.